Change-over switch



E. K. READ CHANGE-OVER SWITCH Filed Sept. 24, 1920 4 Sheets-Sheet l A----L J INVENTOR ATTORNEY WITNESSES:

Oct- ,13, 1925 E. K. READ CHANGE-OVER SWITCH Filed Sept. 24, 1920 4 Sheets-Sheet 2 INVENTOR Ernest/(Feed TToNEY Oct. 13,1925- 1.5573088 E. K. READ CHANGE-OVER swn'cn F11 4 p 1920 4 Sheets-Sheet s WITNESSES: INVENTOR Oct. 13, 1925. 1,557,088

E. K. READ j CHANGE-OVER SWITCH Filod Sept. 24, 1920 4 Sheets-Sheet 4 ENVENTOR Patented Oct. 13, 1925.

UNITED STATES PATENT OFFICE.

Eli-NET I. HELD, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOB "PO 'WB'I'INGHOUSE ELNTRIC & IANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CHANGE-OVER SWITCH.

Application filed September 24, 1920. Serial- No. 412,543.

To all whom it may concern Be it known that I, ERNEST K. READ, a citizen of the United States, and a resident of Wilkinsbur in the county of Allegheny and State of ennsylvania, have invented a new and useful Improvement in Change Over Switches, of which the following is a specification.

My invention relates to changeover switches and particularly to switches used in transferring the load circuit from one supply circuit to another in the event of a reduction in voltage in one of the circuits. I In certain lighting systems, such, for example, as are employed in subways, it is essential that the subways be lighted at all times regardless ofthe failure of the circuit suppl ing the trains with current for power and lighting purposes. An auxiliarzy wer line, receiving its current from a i erent source than the main power line, is associated with the electrical system, for the purpose of supplying current for lighting and other purposes in the emergency of a failure of the main supply circuit.

One object of my invention is to provide a switch mechanism that is responsive to variations in the voltage in the main supply circuit, and that will, upon a predetermined reduction in the voltage in the main supply circuit, open a switch connecting that cir cuit with the load circuit and close a switch closing the auxiliary circuit with the load circuit and transfer the load circuit back to its original supply circuit when the voltage in that circuit returns to normal.

Another object of my invention is to provide a switch mechanism having the above characteristics wherein the switches controlling the su ply circuits are so connected that one switch cannot be closed before the other is fully opened.

A further object of my invention is to provide a switch mechanism of the character described wherein the switches are operated with a snap action.

These and other objects which will be made apparent throughout the further description of the invention are attained by means of the switch apparatus herein described and illustrated in the accompanying drawings, wherein Figure 1 is a front elevational view of one form of the switch mechanism embodying my invention.

Fig. 2 is a bottom view of the switchoperating mechanism shown in Fig. 1.

Fig. 8 is a bottom view of a modified form of switch-operating mechanism.

Fi 4 is an end elevational view of the switc mechanism shown in Fig. 1.

Referring to the drawings, the apparatus includes a panel or base 6 upon which is mounted a pair of movable swltch members 7 and 8. The switch members illustrated in Figs. 1 and 4 are of a standard type Well known in the art, which consists generally of a pair of switch arms 9 and 10 that are ivoted upon stationary terminal-jaw memrs 11 and 12. The arms 9 and 10 are provided with yieldingly mounted contact members 13 and 14, respectively, that engage contact members 15 and 16, which are connected, through the usual blow-out coils 17 and 18, to the terminals 19 and 20 (the former of which is shown in Fig. 4) that are connected to the load circuit.

Current from the main supply circuit and from the auxiliary su ply circuit flows through the switch mem rs 7 and 8 from terminals 21 and 22 (the former of which is shown in Fig. 4). When the switch member 7 is in closed position, the main supply circuit is connected with the load circuit and, when the switch member 8 is in closed position, the auxiliary supply circuit is connected with the load circuit.

Referring to Figs. 1 and 2 wherein one form of switch-operating mechanism is illustrated, the operating mechanism shown includes a pair of overlapped operating levers 23 and 24 that are pivoted adjacent their over-lapped ends by means of a shaft 25 that is mounted upon a frame 26 which surrounds an operating coil or solenoid 6'. The outer ends of the levers 23 and 1'8 pivotally connected to the switch arms 7 and 8, respectively, by means of a universaljoint connection including ad'ustablc rods 27 and 28. The ends of t e rods are threaded and are provided With nuts 29' whereby the positions of the switches 7 and 8 relative to their respective operating levers may be adjusted. The lever 23, for operating the main supply circuit is normally held in closed. position by a .helical spring 30 that is attached, at one end, to the lever 23 and, at the other end, to a bracket 31 that is secured to the frame 26. The

spring 32, attached, at one end, to the overlapped end 33 of the lever 24, and,

at the other end, to the bracket 31, normally tends to move the switch arm 8 to open position. The lever 24 is moved to closed position against the tension of the springs 30 and 32 by means of a core member 34 that is pivoted, at the upper end, to the lever 24 at a point between the pivot shaft 25 and the outer end of the lever. The core -member extends into the coil and causes the lever 24 to move downward to the closed position shown in Fig. 2, when the coil is energized, preferably b current supplied from'the auxilia su p y circuit.

The overlappe en 23 extends above the lever 24 and is .provided with a shoe 36 that is adapted to be engaged by a latch member 37 which is pivoted to the frame 26 by means of the pivot pin 38. The latch is normally held in a position in which it may enga e the shoe 36 by means of the helical spring 39 disposed between the lower extremit of the latch and the frame 26. When ,the lever 24 is moved downward to closed position in response to the energization of the operating coil 26, the end 33 of the lever engages the web 40 carried by the lever 23 and causes opening movement of that lever and the attached switch arm 7. The pivot shaft '25 is so located that the switch arm 7 is entirely withdrawn from the contact member 15 before the switch arm 8 has moved the contact member 14 into engagement with the stationary contact member 16.

When the switch arm 8 has been moved-to closed position, the shoe 36 of the lever 23 is enga ed by the latch 37 and is thereby releasab y retained in open position. The lever 24 is provided with an adjustable screw 41 which may be so adjusted that, when the lever 24 is moved a suflicient distanceto cause the switch 8 to open sufficiently to extinguish the spark incident to the separation of the switch from its contact, the screw 41 engages a projection 42, carried ,upon the inner edge of the latch 37, and trips the latch 37 out of engagement with the shoe 36. The spring 30 then closes the switch arm 7 with a snap action through the medium of the lever 23.

It will be apparent from the foregoing, that normal] the spring 30 retains the switch arm in closed position and the switch arm 8 in open osition by reason of the engagement of t e web 40 carriedby the lever 23, with the end 33 of the lever 24. Energization of the coil 26 causes the switch 7 to be quickly 0 nod and the switch 8 to be subsequent] c osed.

In normal operation, theloafi circuit is supupon a predetermined drop of volta 35 of the member.

plied with current from the main supply circuit through the switch 7. A telly 43 (Fig. 1) that is ermanently connec with the live side of the switch 7, controls the cur rent to the operating coil 26 which is connected to the live side of the switch 8 and receives current from the auxiliary supply' circuit. The relay may be adjusted to close the circuit through the operating coil, in the main supply circuit and Will effect t e transfer of current supply to the load circuit when the volta e in the main sup ly circuit falls below 516 pre'determin amount. When the voltage in the main supply circuit is restored to normal, the current throu h the operating coil is interrrupted by t e action of the relay, which opens the circuit when the voltage in the main supply circuit is restored and the switch 7 is again closed after the switch is opened.

In Fig. 3, I have shown a modified form of s'witch-operati mechanism wherein both the switch control ing the main supply circuit and the switch controlling the auxiliary supply circuit are held wide open until the closed switch has been moved to open position.

In this construction the lovers 23 and 24 are" similar to the correspondin levers employed in the construction il ustrated in .Fig. 2, except that the lever 24 is provided with an extension 45 similar to the extension 35 of the lever 24 shown in Fig. 2) and the screw 41 carri by the lever 24 is mounted upon an intermediate rocking lever.46 that is mounted between the levers 23 and 24. This rocking lever is pivoted upon the shaft 25 upon which the lovers 23 and 24 are also pivotally mounted, and is provided with laterally-extending lugs 47 and 48 that engage the under edges of the levers 23 and 24, respectively.

As shown in Fig. 3, the elements of the mechanism are in the position occupied when the auxiliary supply switch is closed. At this time, the operating coil 26' is energized, and the rocking lever is held in the position shown by means of the core 34 that is attached thereto at a point on the right side of a pivot shaft 25. The lever 24 is held in closed position by a spring 49. At such time, the voltage in the main supply circuit is below the predetermined voltage and the relay has, therefore, closed the circuit through the operating coil 26'.

When the voltage in the main su ply circuit has returned to normal the reliiy 43 is actuated and opens the circuit through the operating coil. The moment the operatin coil is de-energized, the spring 50, that is connected to the left-hand end of the rockinglever 46, turns the rocking lever counterclockwise to move the right-hand end thereof upward. The lug 48, carried by the rock ing lever, engages the under side of the lever 24, an because the spring 50 is stronger than the spring 49, movesthe said lever to open position with a snap action, carrying with it the switch arm .8 controllin .the auxiliary supply circuit.

he screw 41 engages the extension 42 carried upon the latch 37 after the lever 24 has been moved to open position, to trip the latch 37 which has been holding the lever 23 in 0 en position against the tension of the spring 30. The spring 30 causes the switch 7, to which the lever 23 is attached, to close with a snap action. The lever 24 is, at this time, held in open position by the latch 51 which engages a shoe 52 carried by the lever extension 45.

When the relay 43 again closes the circuit through the operating coil, in response to a drop in voltage in the main supply circuit, the rocking lever is turned in a clockwise direction by the core 34. The lug 47 engages the under side of the lever 23 to cause it to be moved to open position with a snap action. When the rocking lever 46 has .moved the lever 23 towide-open position, an adjustable screw 53 carried by the rocking lever trips the latch 51 which permits the lever 24 to be moved to closed position, with a snap action, by the spring 49.

From the foregoing, it will be apparent that the switch mechanism, above described, transfers the load circuit to the auxiliary supply circuit in the event of a predetermined reduction in the voltage in the main supply circuit. The mechanism is such that the switch controlling the main supply circuit is moved to full-open position wherein the spark is extinguished before the switch controlling the auxiliary circuit is moved toclosed position. When the voltage in the main supply circuit is restored to normal, the switch controlling the auxiliary supply circuit is moved to full-open position wherein the spark is extinguished before the switch controllingthe main supply circuit is moved into contact with the stationary contact members. It is, therefore, impossible to connect both circuits with the load circuit at the same time.

While I have described and illustrated but two embodiments of my invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions, additions and omissions may be made in the apparatus described without departing from the spirit and scope thereof, as set forth by the appended claims.

I claim as my invention:

1. Switch mechanism comprising a pair of separate switch members, means normally tending to move the switch members to closed position. latch means for holding one of the switch members in open position and means for tripping the latch to release the said switch member after the other switch member has been moved to open position.

2. Switch mechanism comprising a pair of separate switch members, yielding means normally tending to hold one of the switch members in closed position, latch means for retaining the said switch member in open position, yielding means normally tending to hold the other switch member ope. means for moving the last said switch member to closed position, and for releasably 11etaining it in closed position, and means for tripping the said latch means to release the first said switch member after the last said member has moved to open position.

3. Switch mechanism comprising a pair of separate switch members movable to open and to closed position, separate latch means for releasably latching the said switch mem-' bers in open position, yielding means normally tending to move the said members to closed position, and an operating member for moving a closed switch member to open position and for tripping a latch holding the other member in open position after the closed switch has been moved a predetermined distance.

4. Switch mechanism comprising a pair of separate switch members movable to open and to closed position, means for releasably latching one of the said switch members in open position, yielding means normally tending to move the said members to closed position. a latch for the other switch member, an operating member movable with respect to the said first latch and engaging a closed switch member for mov ing said switch member to open position and for engaging and tripping the second latch holding the other member in open position, after the closed switch has been moved a predetermined distance, and means carried by the said operating member for varying the degree of relative movement between the member and the said first latch.

5. Switch mechanism comprising a pair of separate switch members movable to open and to closed position, a pair of pivotallyconnected operating levers for the switch -members movable to open and to closed position, having overlapping ends, latch members engaging the overlapped ends of he switch members for releasably retainiLg the levers in open position, and means for moving a closed lever to open position adapted to trip the latch retaining the other lever to release the switch after the closed lever has been moved to open position.

6. A change-over switch comprising a switch for connecting a load circuit with a supply circuit, a switch for connecting the said load circuit with an auxiliary sup ly circuit, yielding means for normally ho ding the first switch in closed position and the second switch in open position, means for releasably latching the first switch in open first switch after the second switch has position, electro-magnetic means for closing moved a. predetermined distance. the second switch and opening the first In temimony whereof, I have hereunto 1 switch, and means for moving the second subscribed my name this 7th day of Septem- 6 switch to open position inde ndently of her, 1920.

the first switch, adapted to re ease the said latch to permit closing movement of the ERNEST K. READ. 

